private async Task <byte[]> DownloadAndCacheAsync(string url, string filename, string filepath, TimeSpan?duration)
{
if (duration == null)
{
duration = new TimeSpan(30, 0, 0, 0); // by default we cache data 30 days
}
var data = await _httpClient.GetByteArrayAsync(url).ConfigureAwait(false);
if (data == null)
{
data = new byte[0];
}
if (data.Length == 0)
{
// this is a strange situation so let's not cache this too long: here 5 minutes
duration = new TimeSpan(0, 5, 0);
}
// this ensures the fullpath exists
await _diskCache.AddOrUpdateAsync(filename, data, duration.Value).ConfigureAwait(false);
return(data);
}